The successful application of solid state detectors such as silicon strip detectors for high energy physics experiments was largely due to the development of is multi-channel front-end readout electronics mixed signal Application Specific Integrated Circuits (ASIC) chips, such as the SVX and Amplex chips. Without these monolithic CMOS chips high resolution particle detectors would not be practical. These chips were read out in conjunction with an external trigger supplied by the particle accelerator supplying the particle beam to the experiment. The trigger notifies the control electronics when to read the ASIC chips.
Physics, medicine, materials science, non-destructive evaluation, manufacturing, and environmental science are in need of room temperature, high resolution, and/or position-sensitive radiation detectors. The present scintillator and CCD-based technologies either cannot produce high resolution imaging or do not have the sensitivity. Room temperature radiation detectors are the driving force behind the current effort to develop II-VI semiconductor materials. A room temperature, position-sensitive, high resolution technology such as silicon strip, silicon drift, or silicon pixel detectors coupled to dedicated readout electronics may fill many of the demands of the new detection applications and push radiation imaging to a new level of resolution and flexibility. Unfortunately, the ASIC chips developed for high energy physics experiments cannot be used for most commercial applications such as medical and industrial imaging where an external trigger signal is unavailable.
A front end electronics readout mixed signal ASIC chip normally has a large number of identical channels within a single monolithic chip. The channel number typically ranges from 4 to 256. Newer versions with more channels may be fabricated as narrower (i.e., less than 1 micrometer) processing capabilities become available. One of the principal benefits of these chips is the ability to handle the readout from detectors with extremely large numbers of channels. Because these chips can amplify minute amounts of charge produced by the detectors they are subject to noise problems. In order to reduce the noise, the chips are typically mounted very close to the detector element, strip, pad, or pixel. The detector elements, strips, pads, or pixels are then connected directly or indirectly with the shortest possible length to the input of the ASIC chip. The power supply rails have to be bypassed very close to the ASIC chip as well. The control and output signals are connected to control electronics which controls and interfaces the ASIC chip to the host computer.
Most conventional ASIC chips can only handle low capacitance inputs. They have fixed peaking times, no self trigger output, and either no sparse readout capability or only straight sparse readout capability.
From the foregoing, it is apparent that an ASIC chip which is suitable for use with position sensitive solid state detectors for nuclear instruments is desirable.